Magnum Premium LS broken seat post clamp

mysterymachine

New Member
Region
USA
I got a Magnum Premium LS today, at a bike shop 90 minutes from home. I am new to ebikes, but also only a casual cyclist. Two years ago I bought my first bicycle, which I used for recreation and short commutes, and I don't know a lot about maintaining bicycles.

While I was riding the bike again after I got home, the seat post became loose. It not only slid down to its lowest position, but it was also loose, and would freely rotate. When pulling it back up I saw that there was a white plastic ring that had cracked. I thought maybe it was because of the heat, but the temperature was only around 87 degrees which doesn't seem excessive. (But I am also 170 lbs which may be a bit heavier than the average cyclist...) It seemed to stay in place when I put it back up, but when I got on it, it wasn't long before my weight slid it back down again. I stopped at a local bike shop and asked about it, since I don't know much about repairing bikes, and they tightened the nut, but it didn't seem to help, becuase it went back to being loose after I got on it. The photo is after I got home; on the way back, the broken chunk fell off.

My first bike, a Raleigh Detour 2, also had issues with the seat post not staying up, which it could be fixed by tightening the bolt with a hex wrench. Therefore for the detour, in order to change the height, I have to get out a wrench and loosen it again. I liked that the Magnum didn't require that when I got it at the shop, only needing me to open and lose the lever to adjust the seat. But if it turns out I actually need to use a wrench to change the position of the seat post, this would be a huge inconvenience, because this model of bike requires you to remove the seatpost in order to remove the battery.

I can still ride the bike just fine, because being an ebike, I don't need to use the full power of my legs. Well, the seat swiveling easily and not staying in place is pretty annoying...

I will ask my local bike shop for advice before I make the drive back to the place where I bought it (it was hard for them to diagnose the issue over the phone), but I also wanted to ask here. Google has results on loose/broken seat post clamps, but it's hard to find anything on broken plastic rings, since I don't know what they're called.
 

Attachments

  • seatpost.jpg
    seatpost.jpg
    198.4 KB · Views: 102

AHicks

Well-Known Member
Region
USA
City
Snow Bird - Summer S.E. Michigan, Winter Gulf Coast North Central Fl.
What you have there is a worn out/junk "suspension seat post". These come in a really wide variety of quality and price (20.00-250.00), but most notably, they MUST be ordered in the correct diameter for use on your bike. You'll need to measure very accurately to get the right size.
 

mysterymachine

New Member
Region
USA
It turns out I got the cause and effect backwards... Because it was loose, the seat fell down and broke the ring. It seems that in order for the seat to stay in place, you have to tighten the bolt until you can barely move the lever. I also remembered that with this bike, you can tilt the seat up out of the way so that you can remove the battery.
I will do research on suspension seat posts. Thanks.